-LRB- CNN -RRB- -- Before making judgments about the shootings at Fort Hood , a thorough investigation needs to take place , Sen. John Cornyn of Texas said Thursday .

`` It is imperative that we take the time to gather all the facts , as it would be irresponsible to be the source of rumors or inaccurate information regarding such a horrific event , '' Cornyn said in a statement .

`` Once we have ascertained all the facts , working with our military leaders and law enforcement officials on the ground , we can determine what exactly happened at Fort Hood today and how to prevent something like this from ever happening again , '' he said .

Maj. Nidal Malik Hasan , an Army psychiatrist , shot and killed 11 soldiers and one civilian , officials said . Thirty-one people were wounded , officials at the Army base said . A federal official said Hasan is a U.S. citizen of Jordanian descent .

Cornyn , a Republican , said people should not jump to conclusions about what happened and why .

`` We do not yet have these details , '' the statement said .

President Obama , who was speaking at a conference in Washington , said his administration `` will make sure that we get answers to every single question about this horrible incident . ''

He asked Americans to keep the soldiers and families of Fort Hood in the thoughts and prayers .

Former President George W. Bush , who was governor of Texas from 1995 to 2000 and lives in Crawford about 20 miles from the post , expressed his family 's sorrow .

`` I was saddened to learn of the tragic incident at Fort Hood . Laura and I are keeping the victims and their families in our thoughts and prayers during this difficult time , '' he said .

iReport.com : Are you there ? Send pics , video

Two prominent Muslim organizations condemned the shootings . The Council on American-Islamic Relations , based in Washington , said there was no reason for such violence .

`` We condemn this cowardly attack in the strongest terms possible and ask that the perpetrators be punished to the full extent of the law , '' a statement from the organization said . `` No political or religious ideology could ever justify or excuse such wanton and indiscriminate violence . ''

The Muslim Public Affairs Council offered its sympathy to the victims and their families .

`` MPAC and the Muslim American community unequivocally condemn this heinous incident , '' said a statement from the Los Angeles , California , based group . `` Our entire organization extends its heartfelt condolences to the families of those killed as well as to those wounded and their loved ones . ''

The group said it was working with law enforcement and government officials .

`` American Muslims stand with our fellow citizens in offering both prayers for the victims and sincere condolences to the families of those killed or injured , '' the statement said .

The Secretary of the Army said that while an investigation will come , the well-being of his soldiers was the Army 's first concern .

`` This is a terrible tragedy that we will know more about in the coming days . For now , our focus is squarely on taking care of our soldiers and their families , '' said John M. McHugh in a statement . `` Our thoughts and prayers are with the families and friends of those who have been killed and wounded . The leadership at Fort Hood is marshalling the medical support and counselors necessary to take care of our soldiers and their families and to notify the next of kin . ''

Sen. Kay Bailey Hutchison of Texas said her heart went out to the people affected by the violence .

`` Our dedicated military personnel have sacrificed so much in service to our country , and it sickens me that the men and women of Fort Hood have been subjected to this senseless , random violence , '' said Hutchison , a Republican .

Texas Gov. Rick Perry said the flags of his state would fly at half staff through Sunday .

@highlight

Sen. John Cornyn of Texas says investigation needs to take place

@highlight

President Obama asks Americans to keep soldiers at Fort Hood in their prayers

@highlight

Two Muslim organizations based in the United States condemn the attack

@highlight

Gov. Rick Perry says Texas to fly flags at half staff for rest of week